1. Field of the Invention
The present invention relates to a medical apparatus that electrically drives bending of a bending portion.
2. Description of the Related Art
Various medical apparatuses provided with a bending portion which can be bent have been developed in recent years. For example, an endoscope or treatment instrument provided with a bending portion on a distal end side of an insertion portion which is inserted into a body is widely used in a medical field.
Furthermore, treatment on a lesioned region or the like in the body is performed using a treatment instrument inserted into a treatment instrument channel provided in an endoscope.
Furthermore, treatment may also be performed under observation through an endoscope using a treatment instrument without using any treatment instrument channel.
Furthermore, to improve operability, an active treatment instrument or the like provided with drive means (actuator) to electrically drive a bending portion is commercialized. The medical apparatus such as the active treatment instrument provided with the bending portion on its distal end side adopts a configuration in which the bending portion and the drive means are connected via an angle wire (hereinafter abbreviated as “wire”), the wire is pulled by drive means provided on the operator's hand side so as to drive the bending portion on the distal end side.
In such a configuration, it is structurally difficult to completely avoid looseness in the wire inserted into a flexible and elongated axial portion between the bending portion and the drive means on the operator's hand side so as to enable the wire to be inserted into the body cavity in a bent state. Moreover, the looseness may cause discrepancy between the amount of drive of the drive means on the operator's hand side and the amount of operation of the bending portion on the distal end side.
For this reason, an endoscope disclosed in Japanese Patent Application Laid-Open Publication No. 2000-300511 as a first prior art provides a tension sensor that detects tension acting on the wire to remove looseness of the wire and controls looseness using tension information detected by the tension sensor.
Furthermore, as a second prior art, Japanese Patent Application Laid-Open Publication No. 2007-283115 discloses a control apparatus that removes looseness of a wire whenever the wire is loose to improve the response to an operation command for driving the bending of a bending portion.